impossible obligations check fast path

compiler/rustc_trait_selection/src/solve.rs

@@ -6,6 +6,7 @@ pub mod inspect;
 mod normalize;
 mod select;
 
+pub(crate) use delegate::SolverDelegate;
 pub use fulfill::{FulfillmentCtxt, NextSolverError};
 pub(crate) use normalize::deeply_normalize_for_diagnostics;
 pub use normalize::{deeply_normalize, deeply_normalize_with_skipped_universes};